Electric power tool

Abstract

An electric power tool includes a brushless motor as a driving source. The brushless motor includes a stator and a rotor. The stator includes coils wound around in three phases. In a wire winding method of the coil of the stator, when the number of slots per phase is N, the number of series of the coils per phase is A, and the number of parallel of the coils per phase is B, a relation of N=A×B (note that, N is a natural number of 3 or more and 10 or less, A is a natural number of 1 or more, and B is a natural number of 2 or more) is satisfied.

What is claimed is: 
     
       1. An electric power tool comprising:
 a brushless motor as a driving source, the brushless motor including a stator and a rotor, the stator including coils wound around in three phases, wherein
 in a wire winding method of the coil of the stator, when the number of slots per phase is N, the number of series of the coils per phase is A, and the number of parallel of the coils per phase is B, a relation of N=A×B is satisfied, 
 N is a natural number of 3 or more and 10 or less, A is a natural number of 1 or more, and B is a natural number of 2 or more, and 
 when the number A of the series is two or more, crossover wires between the coils are wired alternately on both front and rear end surfaces of the stator in the axial direction of the stator without intersecting with one another. 
 
 
     
     
       2. The electric power tool according to  claim 1 , wherein:
 in the wire winding method, the number N of the slots is four, the number A of the series is two, and the number B of parallel is two, and 
 terminal wires of the coils of the respective phases are alternately led out with intervals of 60°. 
 
     
     
       3. The electric power tool according to  claim 2 , wherein:
 the stator includes a stator core and insulators, the stator core is made of a magnetic material and the teeth are disposed to protrude on the stator core, and the insulators are each disposed on both end surfaces in an axial direction of the stator core, and 
 the insulator includes a center portion that covers the end surface of the stator core and a radiate portion that covers the end surfaces of the teeth. 
 
     
     
       4. The electric power tool according to  claim 3 , wherein:
 the center portion includes a pair of protrusions projecting from both sides of a base of the radiate portion and a ring-shaped rib positioned on an inner side of the protrusions, and the protrusions and the rib are each disposed to protrude on the center portion, and 
 the crossover wires between the coils are led passing between the protrusions and through an outside of the rib. 
 
     
     
       5. The electric power tool according to  claim 4 , wherein
 the crossover wires between the coils are disposed only on an opposite connection side of the stator and intersect with one another.